Objectives: To determine the contribution of dermal absorption on the total exposure dose and the performance of respirators in the field for xylene in spray painters.
Methods: Eighteen male spray painters worked at shipyard were recruited for this study. The subjects were monitored during a 3-day-work period using a repeated-measures study design. Personal exposure to xylene outside and inside mask were collected using two 3 M model 3500 organic vapor monitors, respectively. Urine was collected before and after the work shift and urinary methyl hippuric acid (MHA) was determined. Total 98 of air and urine samples were obtained, respectively.
Results: Air sampling results showed that workers were primarily exposed to xylene and ethyl benzene. Xylene and ethyl benzene concentrations outside the mask were 52.6+/-63.7 (mean+/-SD) and 33.2+/-32.4 ppm, and concentrations inside the mask were 2.09+/-2.74 and 1.79+/-2.16 ppm, respectively. The median workplace protection factors of respirators for xylene and ethyl benzene were 25.0 and 17.4, respectively. On average, workers could reduce xylene inhalation by 96% and ethyl benzene inhalation by 94% for wearing respirators. A significant correlation (R(2)=0.935; P<0.001) was found between the WPFs for xylene and ethyl benzene. Total urinary MHA concentration was 240.2+/-42.3 (mean+/-SE) mg/g creatinine, whereas urinary MHA via skin absorption was estimated to be 202.1+/-40.1 mg/g creatinine. The contribution of dermal absorption to the total exposure dose of xylene was 64+/-4.3%.
Conclusion: The present study showed that inhalation of solvent vapors in workers decreased as a result of wearing respirators and dermal exposure became the main contributor to the total body burden of solvents. Because workers had different attitude and behavior to wear respirators, the measured workplace protection factors varied. It is therefore equally important to prevent from being exposed to solvents through skin for shipyard spray painters.